In order to treat a variety of medical conditions, insertable or implantable medical devices having a coating for release of a biologically active material have been used. For example, various types of drug-coated stents have been used for localized delivery of drugs to a body lumen. See U.S. Pat. No. 6,099,562 to Ding et al. Such stents have been used to prevent, inter alia, the occurrence of restenosis after balloon angioplasty. However, delivery of the biologically active material to the body tissue immediately after insertion or implantation of the stent may not be needed or desired. For instance, it may be more desirable to wait until restenosis occurs or begins to occur in a body lumen that has been stented with a drug-coated stent before the drug is released. Therefore, there is a need for implantable medical devices that can provide on-demand delivery of biologically active materials when such materials are required by the patient after implantation of the medical device. Also needed is a non-invasive method to facilitate or modulate the delivery of the biologically active material from the medical device after implantation.